In relatively large moulding machines, it is usual to have a platen (usually vertical) which carries on it a moulding die, and if the moulding is large dimensionally the die usually requires multiple injection points. Heated polymeric material is fed to these injection points, and injected through nozzles and into a die cavity, the nozzles being provided with hydraulically actuated valve means to control the injection flow.
There is a heated flow transportation and control system for the polymeric material which is normally attached to the die, but it sometimes comprises a manifold attached to the front face of the platen, where dies engage it independently for different moulding requirements. A master valve assembly (termed a "valve gate") controls flow to the injecting nozzles.
However, because of the existence of the master valve assembly, the requirement to heat the manifold in order to retain the polymeric material in fluent form within it, and the space occupied by hydraulic control means of the shut-off pins at the injecting nozzle locations and also the master valve assembly, the overall depth is considerable, and this reduces the distance between platens, in turn placing dimensional limits on the tools which can be utilised, and their handling equipment.
The main object of this invention is to provide improvements whereby, firstly, the capacity size of a moulding machine is not so reduced, and a larger die can be utilised in a machine, secondly, whereby the location of the injection points for a die can be varied to be most suitable for that die, and thirdly whereby the platen face remains available for the securing of dies or their accessories.